| abstract |
A system for detection of base contamination at low concentrations in air comprises a detector that provides a single reading that is stoichiometrically related to the aggregate proton-bonding characteristic of various base contaminants present in the air. The system can operate as a "total amine detector" for air-borne amines, and in important implementations is employed in semiconductor manufacturing, e.g. in respect of incoming or exhaust air from a cleanroom or in respect of the stepper or coat and develop track of a photolithographic process. The system comprises a converter for converting all amines present in the air to a common detectable compound detected by the detector. In various implementations additional features are shown. The converter is located near a sample region of a process and the detector is remotely located with sample lines extending between converter and detector to conduct a sample flow. Filters provide air free of amine contaminants to various stages of a process. The air from the outlet of the filters is employed to provide zero air for calibration of the converter and detector. Continual, automated recalibration is shown. Air from the intermediate port of the filters and air from the outlet are employed to monitor the remaining filter capacity and to verify the fidelity of the zero air reference. In other implementations, the detection system is constructed as a mobile detection unit. In another implementation, the detection system is constructed to monitor total amine concentration at selected stages of a multistage manufacturing process. |